Arriving home at dawn after another failed burglary, John Dortmunder—the anti-hero of Donald Westlake's popular comic crime series—is shocked to find his apartment occupied by a notorious cellmate everyone had supposed (and hoped) had been jailed for life. Tom Jimson needs Dortmunder's help.

Thirty years ago, before his last prison stretch, Tom had pulled a big job up near Albany—a very big job—that left a cool $700,000 in cash buried under a water reservoir in an upstate New York valley. Being the nasty sort of fellow he is, Tom's plan is to blow up the dam, flood the surrounding countryside, and grab the cash. With the fate of 900 small town nobodies hanging in the balance, Dortmunder races against Tom's itchy dynamite finger to formulate an alternative plan for retrieving the loot. Thus begins a convoluted caper, in the Westlake tradition, of misadventure and hilarity.